Office of Research

Appendix B

GUIDELINES FOR THE

STORAGE OF LABORATORY CHEMICALS

  

The safe storage of laboratory chemicals is a vital concern for most laboratories. Many problems have occurred when chemicals are assumed to be static and inert once placed in their stationary positions in the storage cabinet or storeroom. Chemicals, especially laboratory chemicals, have a tremendous hazard potential entailing special requirements to avoid accidents. A safe storage process anticipates these requirements and provides the appropriate environment, procedures, and controls to prevent leaks, spills, and the release of hazardous energy from laboratory chemicals.

Always consult the product label, Safety Data Sheet, and any other source of available information to obtain information on the proper storage of hazardous materials.

There are nine key elements to a safe chemical storage program:

  1. Maintain an inventory of all chemicals in the lab.
  2. Ensure that all chemicals are properly labeled.
  3. Separate incompatible chemicals and equipment.
  4. Ensure that all chemicals are stored in containers that are appropriate for the chemical being stored.
  5. Store all chemicals in the proper chemical storage cabinets, safety cans, locked cabinets, etc., where required.
  6. Secondary containment is always a prudent practice, but must be provided when needed to ensure separation of incompatible chemicals.
  7. Post all storage rooms, cabinets, etc., with the proper signage to indicate the hazards of the chemicals being stored
  8. Post emergency procedures and telephone numbers nearby.
  9. Routine inspections are performed to ensure that containers are properly labeled; not deteriorating; chemicals which have become dangerous or formed dangerous by-products are removed; and other chemicals exceeding their expiration dates or are no longer useful product are disposed of properly.

storage diagram

Storage Restrictions

The amounts of toxic, flammable, unstable, or highly reactive materials that should be permitted in laboratories are an important concern. To arbitrarily restrict quantities may interfere with laboratory operations, but conversely, unrestricted quantities can result in the undesirable accumulation of such materials in the laboratory. The amounts of certain chemicals such as flammable liquids and compressed gases are controlled by the National Fire Protection Association (NFPA). The Occupational Health and Safety Administration regulations for the laboratory storage of flammable and combustible liquids are not based on fire prevention and protection principles, but rather address the types and sizes of containers allowable. 

The following minimum restrictions apply to all laboratories: 

  • No more than 10 gallons of flammable chemicals (including waste) stored in containers other than approved safety cans may be kept in laboratories outside of chemical storage cabinets at any one time.
  • Up to 10 additional gallons can be kept in the laboratory, outside of an approved flammable storage cabinet, if the quantity in excess of 10 gallons is stored in approved safety cans not to exceed two gallon capacity.
  • Quantities in excess of 25 gallons must be kept in the protection of approved flammable storage cabinets.
  • Amounts in excess of 60 gallons per laboratory should be stored in an approved chemical storage room.
  • All chemicals in laboratories should be in containers that are 8L or less. Larger containers (i.e., 20L) are too large for safe handling. Most laboratory chemicals need to be dispensed/used inside a chemical hood, glove box, etc. Containers that are too large present ergonomic hazards, as well as increased chances of spills.

 

Flammable storage cabinets should be used to store all flammable and combustible liquids in the laboratory, including those in safety cans unless they are in immediate use. No more than an one-week supply of flammable liquids should be kept in the laboratory at one time. Flammable storage cabinets are designed to protect the contents from external fires. Therefore, the door(s) must be kept closed except when removing or replacing chemicals. Doors must close properly. If doors do not close properly, they should be repaired immediately. The interior of these cabinets is capable of withstanding the effects of vapors from solvents, but not of other materials, such as corrosives. These materials are incompatible with most flammables. Only flammable materials should be kept in flammable storage cabinets.

 

Inspection of Stored Chemicals:

All stored chemicals should be examined at periodic intervals (at least quarterly). At this time, those that have been kept beyond their appropriate shelf life or have deteriorated, have questionable labels, are leaking, have corroded caps, or have developed any other problem should be disposed according to university hazardous waste management procedures. During this inspection, the inventory of chemicals present in the laboratory or storage area shall be updated or verified and the date and name of the inspector recorded.

Chemicals showing any of the indications listed below shall be turned over to the RS Hazardous Waste Management group for safe disposal:

  • Spotting on solids
  • Caking of anhydrous materials
  • Pressure buildup in containers
  • Evidence of reaction with water
  • Corrosion of damage to the container
  • Existence of unusual solids in liquids or liquids in solids
  • Precipitate (crystals around neck or cap of bottle) of shock-sensitive compounds

 

Dating of Chemical Containers

All chemicals should be dated when they are received and when they are opened. Chemicals known to decompose over time to dangerous states or by-products should have auxiliary labels added, with additional information including warnings and expiration dates. It is a prudent practice to have “decision dates” or estimated dates of expiration on all chemicals. When the “decision date” is reached, the chemical could be reevaluated to determine whether the chemical should be kept or removed for proper disposal. This information provides a history of the chemicals in each container and guides future researchers as to potential quality of the chemicals stored in the laboratory.

 

SHELF STORAGE

  • Large bottles and containers are stored on shelves no higher than 2 feet from the floor.
  • Containers of corrosive chemicals are stored below eye level
  • Shelves have raised edges or rim guards to prevent the accidental dislodging of containers.
  • Only chemicals of low toxicity are stored on open shelves. Toxic and highly toxic chemicals should be stored in closed cabinets. Highly toxic chemicals should be stored in ventilated cabinets and secondarily contained.
  • Reagent bottles or containers do not protrude over the shelf edges.
  • Enough space is available so that chemicals are not overcrowded.
  • Empty bottles are removed from stockroom shelves
  • Shelves are level and stable. Shelving units are securely fastened to wall or floor.
  • Weight limit of shelves is not exceeded.
  • Shelves are clean, free of chemical contamination.
  • Secondary containers large enough to collect contents of containers, if necessary. Only compatible chemicals should be stored together in secondary containers when secondary containers are used to hold more than one product.
  • Do not store chemicals alphabetically except within hazard categories.

 

STORAGE CONTAINERS

  • Storage containers are inspected periodically for rust, corrosion, or leakage.
  • Damaged containers are removed or repaired immediately.
  • Chemicals are kept in airtight bottles, not in beakers or open or improperly capped containers.
  • Carboys used for storing chemical solutions have spigots that are leak tight and drip free. Secondary containment (i.e., tubs, drip cups, etc.) should be used.
  • Dispensing tubes on carboys are free or corrosion or aging.
  • Storage containers are appropriate for the materials being stored.

 

LABELING OF CHEMICAL CONTAINERS

  • All containers are clearly labeled as to contents (name of the chemical, no abbreviations, etc.)
  • Labels are legible and free of encrustation or contamination.
  • Labels are firmly attached to containers.
  • Chemical containers are labeled with the appropriate warning (e.g., poison, corrosive, flammable, etc.)
  • All container labels include both date of receipt. Recording a date when chemicals are opened is necessary for chemicals that become dangerous or form dangerous by-products over time and is a prudent practice for all chemicals.
  • It is a prudent practice to include precautionary measures and PPE required for handling the specific chemical
  • Labels should be written in English.

 

HOUSEKEEPING

  • Cleanliness and order are maintained in the storage area and laboratory at all times.
  • Unlabeled, contaminated, or undesirable chemicals are discarded properly.
  • Unused chemicals are never returned to stock bottles.
  • Packing materials and empty cartons are removed at once from the stockroom or laboratory.
  • Waste receptacles are properly marked and easily located.
  • Separate disposal containers are available for broken glass. (These must be sturdy, puncture-resistant containers and they must be labeled)
  • Chemical, equipment, etc. should be kept off of laboratory floor space and aisles.

 

CHEMICAL STORAGE

  • Chemicals should not be exposed to direct sunlight or localized heat.
  • Chemicals should be separated and stored according to chemical family or hazard classification. Chemicals must also be segregated properly within chemical families whenever necessary, for example: strong mineral acids and strong alkaline materials are both corrosive and may be labeled as such; they should not, however, be stored together, since they would react vigorously if accidentally mixed.
  • All incompatible chemicals must be physically segregated from each other during storage.

 

            ACIDS

Acids require special storage because they are corrosive and some are oxidizers. There are two main groups of acids, organic acids, and inorganic (mineral) acids. Some inorganic acids are oxidizers and will react with organics. Therefore, as a rule of thumb, inorganic acids should be stored separately from organic acids and other chemicals.

Examples of inorganic acids:

*Oxidizers

    • Perchloric acid
    • Chromic acid
    • Sulfuric acid
    • Nitric acid

 

        *Non-oxidizers:

    • Hydrochloric acid
    • Hydrofluoric acid
    • Phosphoric acid

 

      Examples of organic acids:

    • Acetic acid
    • Formic acid
    • Butyric acid
    • Propionic acid
    • Picric acid
    • Acrylic acid

 

Organic acids (e.g., glacial acetic acid) are combustible and should be stored separately or with flammables (secondarily contained) rather than with inorganic acids. Several inorganic acids are oxidizers and, therefore, incompatible with organics.

  • Large bottles of acids should be stored on low shelves or in acid cabinets.
  • Oxidizing acids are segregated from organic acids and flammable and combustible materials.
  • Acids are separated from caustics and from active metals such as sodium, magnesium, and potassium.
  • Acids are segregated from chemicals that can generate toxic gases on contact, such as sodium cyanide and iron sulfide.
  • Absorbents or acid neutralizers appropriate for acids stored should be available for acid spills.

 

            CAUSTICS

    • Caustics are stored away from acids.
    • Solutions of inorganic hydroxides are stored in polyethylene containers.
    • Appropriate absorbents or caustic neutralizers are available for spills.

  

            FLAMMABLES

            Flammable materials have a flash point between 20-100F.

    • All flammable liquid containers are in compliance with the maximum container sizes found in the table at the end of this appendix.
    • NFPA specified safety cabinets are used for the storage of flammable liquids 
    • Flammables are kept away from and source of ignition: flames, heat, or sparks.
    • Approved refrigerators are used for storing flammable liquids.
    • Appropriate absorbents are available for small spills or leaks.

 

Bonding and Grounding:

Bonding and grounding is the process of providing an electrically conductive path between a dispensing container, a receiving container, and an earth ground. This pathway eliminates the potential buildup of static electricity and possible spark that can cause a flash fire if there is a flammable mixture of fuel and air.

Read about applicable requirements and definitions, and how to ground and bond below. Glass containers are excluded.

Requirement

Class 1 Flammable Liquids must be bonded and grounded when transferring liquids in accordance with Code of Federal Regulations, 29 CFR 1910.106(e)(6)(ii):

"Grounding." Class I liquids shall not be dispensed into containers unless the nozzle and container are electrically interconnected. Where the metallic floorplate on which the container stands while filling is electrically connected to the fill stem or where the fill stem is bonded to the container during filling operations by means of a bond wire, the provisions of this section shall be deemed to have been complied with.”

Definitions

  • Bonding is the process of connecting 2 or more conductive objects together by means of a conductor so that they are at the same electrical potential, but not necessarily at the same potential as the earth [NFPA 77 - 3.1.2].
  • Grounding is the process of bonding 1 or more conductive objects to the ground, so that all objects are at zero (0) electrical potential; also referred to as "earthing" [NFPA 77 - 3.1.10].
  • Grounding plate is a metal plate used to provide a bond for the receiving container.
  • Grounding rod is an easily cleaned nonreactive metal rod designed to provide a bonding point for containers that are too small or that have no metal attachment point.
  • Static electric discharge is a release of static electricity in the form of a spark, corona discharge, brush discharge, or propagating brush discharge that might be capable of causing ignition under appropriate circumstances [NFPA 77 3.1.16].

How to bond and ground

  • See Lab Safety Supply's Bonding and Grounding Fact Sheet for a good overview reference.
  • Carefully assess and identify a safe location, avoiding:
    • Poorly ventilated spaces
    • Open flames or heat sources (e.g., hot plates, Bunsen burners etc.)
    • Electrically charged equipment
  • Transfer flammable liquids within a chemical fume hood when possible and in a proper dispensing location such as a high hazard room (flammable room) or well-ventilated laboratory room.
  • Use proper bonding and grounding cables:
    • Plastic coated 10' coiled grounding cable with clamps on both ends work well (see image below). Some locations may have permanent cables available.
    • Braided 3' bonding cable with alligator clips on both ends work well (see image below).
  • Find an earth ground (copper water lines work well) and label it for future reference. Do not use fire sprinkler lines!
  • Remove dirt, debris, paint, etc., to ensure a good metal to metal connection.
  • Connect the dispensing vessel to the earth ground.
  • Place receiving vessel in a secondary container or on a bonding metallic floorplate.
  • Connect the bonding cable from the receiving vessel to the dispensing vessel or floorplate (metal to metal).
    • Note: If the receiving container is too small, does not have a metal connection, or you do not have a metal floorplate, provide a grounding rod (use care that it does not tip over).
  • Once properly connected, proceed with your transfer.
  • When complete, disconnect all bonding and grounding cables and remove the grounding rod if applicable.
  • Clean all equipment and properly transport the material to the laboratory.
  • Leave the bonding and grounding equipment readily available for the next person to use.

grounding example 1bonding example 2


2 examples of bonding and grounding configurations.

 

 PEROXIDE-FORMING CHEMICALS

  • Peroxide-forming chemicals are stored in airtight containers in a dark, cool, and dry place.
  • Peroxide-forming chemicals are properly disposed of before the date of expected peroxide formation.
  • Peroxide-formers are labeled with date received, date opened, and disposal date.
  • If peroxide contamination is suspected, do not pick up, shake, or otherwise disturb the container. Call and report this information to RS.
  • Peroxide-formers should be checked for the presence of peroxides with either wet chemicals or test strips when opened. The checks should be conducted prior to heating the solvent and after each month of storage.

 

WATER-REACTIVE CHEMICALS

            These chemicals will react vigorously with water to yield heat, flammable or toxic gases or other hazardous conditions.

    • Chemicals are kept in a cool, dry place.
    • Water-reactive chemicals containers are kept tightly closed and secondarily contained in a water-tight container if contact with water is possible.
    • In case of fire, a Class D fire extinguisher should be used if personnel have been trained to use fire extinguishers, and it is judged that the fire is small enough to be handled by departmental personnel.

 

            The following are some common laboratory chemicals that react violently with water:

            Alkali metals

            Alkali metal hydrides

            Alkali metal amides

            Metal Alkyls, such as lithium alkyls and aluminum alkyls

            Grignard reagents

            Halides of nonmetals, such as Boron Trichloride and Boron Trifluoride

            Inorganic acid halides

            Anhydrous metal halides such as Aluminum chloride

            Phophorous pentoxide

            Calcium carbide

            Organic acid halides and anhydrides of low molecular weight

 

OXIDIZERS

  • Oxidizers are stored away from flammable, combustible, and reducing agents (e.g., zinc, alkaline metals).
  • Oxidizers react vigorously with reducing materials. This reaction can lead to fires or explosions.

Examples:

  • Halogens
  • Ammonium persulfate
  • Sodium dichromate
  • Hydrogen peroxide
  • Potassium permanganate
  • Perchloric acid

PYROPHORIC CHEMICALS

  • Should be stored in tightly closed containers under an inert atmosphere (or, for some, in an inert liquid).
  • All transfers and manipulations of them must be carried out under an inert atmosphere or liquid.

 

            Examples are:

            Grignard reagents, RMgX

            Metal alkyls and aryls, such as RLi and RNa

            Metal carbonyls

            Alkali metals such as Potassium and Sodium

            Metal powders, such as Aluminum, Iron, Magnesium, and Zinc

            Metal hydrides

            Nonmetal hydrides, such as Diborane and Arsine

            Nonmetal alkyls

            Phosphorus (white)

 

POLYNITRO COMPOUNDS

Many polynitroaromatic compounds are shock-sensitive as are some aliphatic compounds containing more than one nitro group. Many of these compounds are sold and stored with 10 to 20 percent water, which desensitizes their reaction to shock, although they are still flammable solids.

Polynitro compounds shall be stored separately from most chemicals and labeled so they will be easily identified as reactive. They shall not be placed in long-term storage without special posting indicating their presence and removal date. Long-term storage without checking for proper water content may allow the compounds to dehydrate sufficiently to make them highly reactive.

Surplus and waste polynitro compounds shall be given to RS promptly for proper disposal and not left on a shelf to be forgotten.

If old containers of polynitro compounds are found, including picric acid or dinitrophenyl hydrazine, do not move them without consulting RS.

Picric Acid. Dry picric acid is highly explosive and should be brought into the laboratory only when specifically required. Users should have a thorough understanding of its hazards. Although not explosive when wetted, picric acid solutions may evaporate to leave the hazardous solid. Properly hydrated picric acid will have a moist, yellow appearance. The weight of a new bottle of picric should be recorded on the label before opening, and again each time before and after removing any material for use. Water should be added as a matter of course. If the tare weight has decreased markedly between usages, it may be attributed to the loss of water and resulting instability. Picric acid should be stored away from combustible materials and should not be kept for extended periods (any material older than two years should be disposed). Old containers of picric acid should not be moved or handled - contact RS.

 

TOXIC COMPOUNDS

  • Toxic compounds are stored according to the nature of the chemical, with appropriate security employed where necessary.
  • A Poison Control Network telephone number should be posted. (1-800-922-1117)

 

STOCKROOMS

1.     Stockrooms should be usually within or close to the areas served. Stockrooms should not be used as preparation or dispensing areas because of the possibility that an accident will occur and thereby unnecessarily contaminate a large quantity of materials.

2.     Stockrooms should be conveniently located and open during normal working hours so that laboratory personnel need not store excessive quantities of chemicals in their laboratories.

3.     Procedures must be established for the operation of any stockroom that place responsibility for its safety and inventory control in the hands of one person. This person should be readily available. A backup person should be established to perform these duties when the stockroom manager is not available.

4.     Stockrooms should be well ventilated, with exhaust air leaving the building.

5.     Stockrooms must be properly marked or identified.

6.     Stockrooms must be secured whenever not in use and are available only to authorized personnel.

7.     Stockrooms should have two or more clearly marked exits.

8.     Properly dispose of outdated chemicals.

9.     Stockrooms must be well illuminated and free of blind alleys.

10.  All electrical service equipment should be explosion-proof for the appropriate class and group of flammable liquids.

11.  Containers of flammable liquids are properly grounded and bonded for storage and dispensing.

 

FLAMMABLE LIQUID CLASSIFICATION

CLASS

FLASH POINT (oF)

BOILING POINT (oF)

      IA

Below 73

Below 100

      IB 

Below 73

At or above 100

      IC

At or above 73, below 100

NA

       II

At or above 100, below 140

NA

     IIIA

At or above 140, below 200

NA

     IIIB

At or above 200

NA

 

             MAXIMUM ALLOWABLE SIZE OF FLAMMABLE              
AND COMBUSTIBLE
             LIQUID CONTAINERS IN LABORATORIES
 
 

           FLAMMABLE LIQUIDS

    COMBUSTIBLE LIQUIDS

  CONTAINER             

CLASS IA

CLASS IB

CLASS IC

    CLASS II 

     CLASS III

Glass

1 pinta

1 quarta

1 gallon

1 gallon

5 gallons

Metal (other than DOT drums) or approved plastic

1 gallon

5 gallonsb

5 gallonsb

5 gallonsb

5 gallons

Safety cans     

2 gallons

5 gallonsb

5 gallonsb

5 gallonsb

5 gallons

Metal drum (DOT Spec.)

Not allowed

5 gallonsb

5 gallonsb

60 gallonsb  

60 gallons

aGlass containers of not more than one-gallon capacity are acceptable if the required purity would be affected by storage in metal or if excessive corrosion would result from storage in metal.

 

bIn instructional laboratory work areas, no container for Class I or II liquids shall exceed a capacity of one-gallon, other than safety cans which may be of two-gallon capacity.

  

Reference:  NFPA 45, Fire Protection for Laboratories Using Chemicals, National Fire Protection Association, 1991.

Incompatible Chemicals*

 

The following list is to be used only as a general guideline.  Please refer to your Safety Data Sheets (SDS) for specific incompatibilities.

 

 

Chemical:

Incompatible with:

Acetic acid

Chromic acid, nitric acid, hydroxyl compounds, ethylene glycol, perchloric acid, peroxides, permanganates

Acetylene

Chlorine, bromine, copper, fluorine, silver, mercury

Acetone

Concentrated nitric and sulfuric acid mixtures

Alkali and alkaline earth metals

Water, carbon tetrachloride or other chlorinated hydrocarbons, carbon dioxide, halogens

Ammonia (anhydrous)

Mercury, chlorine, calcium hypochlorite, iodine, bromine, hydrofluoric acid (anhydrous)

Ammonium nitrate

Acids, powdered metals, flammable liquids, chlorates, nitrites, sulfur, finely divided organic combustible materials

Aniline

Nitric acid, hydrogen peroxide

Arsenic materials

Any reducing agent

Azides

Acids

Bromine

See chlorine

Calcium oxide

Water

Carbon (activated)

Calcium hypochlorite, all oxidizing agents

Chlorates

Ammonium salts, acids, powdered metals, sulfur, finely divided organic or combustible materials

Chromic acid and chromium trioxide

Acetic acid, naphthalene, camphor, glycerol, alcohol, flammable liquids in general

Chlorine

Ammonia, acetylene, butadiene, butane, methane, propane(or other petroleum gases), hydrogen, sodium carbide, benzene, finely divided metal, turpentine

Chlorine dioxide

Ammonia, methane, phosphine, hydrogen sulfide

Copper

Acetylene, hydrogen peroxide

Cumene hydroperoxide

Acids (organic or inorganic)

Cyanides

Acids

Flammable liquids

Ammonium nitrate, chromic acid, hydrogen peroxide, nitric acid, sodium peroxide, halogens

Fluorine

All other chemicals

Hydrocarbons (such as butane, propane, benzene)

Fluorine, chlorine, bromine, chromic acid, sodium peroxide

Hydrocyanic acid

Nitric acid, alkali

Hydrofluoric acid (anhydrous)

Ammonia (aqueous or anhydrous)

Hydrogen sulfide

Fuming nitric acid, oxidizing gases

Hypochlorites

Acids, activated carbon

Iodine

Acetylene, ammonia (aqueous or anhydrous),  hydrogen

Mercury

Acetylene, fulminic acid, ammonia

Nitrates

Acids

Nitric acid (concentrated)

Acetic acid, aniline, chromic acid, hydrocyanic acid, hydrogen sulfide, flammable liquids and gases, copper, brass, any heavy metals

Nitrites

Acids

Nitroparaffins

Inorganic bases, amines

Oxalic acid

Silver, mercury

Oxygen

Oils, grease, hydrogen; flammable liquids, solids, and gases

Perchloric Acid

Acetic anhydride, bismuth and its alloys, alcohol, paper, wood, grease, oils

Peroxides, organic

Acids (organic or inorganic), avoid friction, store cold

Phosphorus (white)

Air, oxygen, alkalis, reducing agents

Potassium

Carbon tetrachloride, carbon dioxide, water

Potassium chlorate

Sulfuric and other acids

Potassium perchlorate see also chlorates

Sulfuric and other acids

Potassium permanganate

Glycerol, ethylene glycol, benzaldehyde, sulfuric acid

Selenides

Reducing agents

Silver

Acetylene, oxalic acid, tartaric acid, ammonium compounds, fulminic acid

Sodium

Carbon tetrachloride, carbon dioxide, water

Sodium nitrite

Ammonium nitrate and other ammonium salts

Sodium peroxide

Ethyl or methyl alcohol, glacial acetic acid, acetic anhydride, benzaldehyde, carbon disulfide, glycerin, ethylene glycol, ethyl acetate, methyl acetate, furfural

Sulfides

Acids

Sulfuric acid

Potassium chlorate, potassium perchlorate, potassium permanganate (similar compounds of light metals, such as sodium, lithium)

Tellurides

Reducing Agents


CHEMICAL STORAGE GUIDELINES* 

STORE MATERIALS OUTLINED BY BOXES SEPARATELY

compatability chart